#include <iostream>
#include <string>

using namespace std;

int main()
{
    string str1 = "string1";
    string str2 = "string2";
    string str_out = "";

    // First way
    str_out = str1 + str2;
    cout << str_out << endl;

    // Second way
    str_out.append(str1);
    str_out.append(str2);
    cout << str_out << endl;
    return 0;
}